#include <stdio.h>
#include <math.h>
int main()
{
    int a, i, b, n;
    printf(" there are following friendly -numbers pair samller than 3000:\n");
    for (a = 1; a < 3000; a++)
    {
        for (b = 0, i = 1; i <= a / 2; i++)
            if (!(a % i))
                b += i;
    for (n = 0, i = 1; i <= b / 2; i++)
        if (!(b % i))
            n += i;
    if (n == a && a < b)
        printf("%4d..%4d", a, b);
}
}